METHODS OF EXAMINATION 535 



countries. It is characterised by pyrexia, darkly-coloured urine, 

 the colour being due to altered haemoglobin pigment, delirium 

 and collapse, frequently ending in coma and death. By some 

 the condition has been looked on as a separate disease, by others 

 as the terminal stage of a severe malaria. With regard to the 

 former view no special parasite has yet been demonstrated. 

 Stephens sums up the evidence for the second view by saying 

 that malaria, apart from the occurrence of blackwater fever, is a 

 relatively non-fatal disease, that in the great majority of cases 

 there is direct or indirect evidence of the subject of the condition 

 having suffered from repeated attacks of malaria, that while in 

 all cases there must be an agent at work causing hadinolysis, 

 there is evidence that in many cases there is the possibility of 

 that agent being quinine. This last point is of great interest. 

 It has been shown that in certain individuals the taking of this 

 drug is sometimes followed by hsemoglobinuria. The conditions 

 under which this occurs are unknown, and in the case of black- 

 water patients, neither is the serum haemolytic for normal 

 corpuscles, nor do the red corpuscles seem to be specially 

 sensitive to haemolysis by quinine, in fact, the latter do not 

 appreciably differ from ordinary red cells. The whole subject 

 of the pathology of the condition is thus very obscure. 



Methods of Examination. The parasites may be studied by 

 examining the blood in the fresh condition, or by permanent 

 preparations. In the former case, a slide and cover-glass having 

 been thoroughly cleaned, a small drop of blood from the finger 

 or lobe of the ear is caught by the cover-glass, and allowed to 

 spread out between it and the slide. It ought to be of such a 

 size that only a thin layer is formed. A ring of vaseline is 

 placed round the edge of the cover-glass to prevent evaporation. 

 For satisfactory examination an immersion lens is to be preferred. 

 The amoaboid movements are visible at the ordinary room 

 temperature, though they are more active on a warm stage. 

 With an Abbe condenser a small aperture of the diaphragm 

 should be used. 



Permanent preparations are best made by means of dried 

 films. A small drop of blood is allowed to spread itself out 

 between two cover-glasses, which are separated by sliding the 

 one on the other. The films are then allowed to dry. A very 

 good method is that of Manson, who catches the drop of blood 

 on a piece of gutta-percha tissue (a piece of cigarette-paper also 

 does well), and then makes a film on a clean slide by drawing 

 the blood over the surface. The dried films are then fixed by 

 one of the methods already given (p. 87), or by placing in 



